Analytical and Experimental Investigation of Torsional Vibrations in Variable Frequency Drive Controlled Induction Motor Driven Machinery

The prediction and control of torsional vibrations in rotating machinery is essential for preventing resonance related failures. Variable Frequency Drives (VFDs) are increasingly used to control the speed of induction motors, offering operational flexibility but also introducing undesirable torque harmonics. These harmonics, generated by the interaction of switching and carrier frequencies, can coincide with system natural frequencies and excite damaging vibration amplitudes. The research done enhances the VFD Software to better predict and analyze such excitations. A synchro-self-shifting (SSS) clutch modeling capability is integrated into the software, enabling automatic synchronization and torque transfer within machinery trains and allowing engagement responses in multi-source systems to be simulated. Additional improvements include expanded error-handling routines that issue warnings to prevent invalid inputs, and the option to generate API 617 compliant torsional reports. To validate the predictions, two experimental test rigs are employed. The first rig uses a hysteresis brake to measure torque harmonics in an induction motor driven system with a rigid coupling. The second rig is newly designed and fabricated to replace the hysteresis brake with a low inertia eddy current brake, allowing improved measurement of dynamic responses. In both setups, the experimentally observed torque spectra confirm the presence of harmonics predicted by Song's equations which align closely with the software's numerical results. These findings demonstrate that the developed framework can accurately capture VFD-induced excitations and provide a reliable basis for evaluating system resonance risks. Overall, the combination of enhanced software modeling and validated test rigs establishes a practical toolset for analyzing torsional vibrations in VFD-driven machinery, contributing to safer and more reliable operation of rotating equipment across industrial applications.

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

Texas A&M University

Year dc:date.issued

2025

Author dc:creator

• Ahmed, Mohammed Junaid 2000-

Advisor dc:contributor.advisor

• Palazzolo, Alan

Committee members dc:contributor.committeemember

• Toliyat, Hamid
• Liang, Hong

• Engineering, Mechanical

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/1600527

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F1600527